Travel route generation device and travel route generation method

ABSTRACT

A travel route generation device includes circuitry configured to define a shape of a work field by calculating a first line connecting a starting point and one of intermediate points, and a second line connecting another of the intermediate points and an end point. The circuitry is configured to calculate a shape of an entrance passage in the work field though which a work vehicle is to enter a target work region in which the work vehicle is to work in the work field. The entrance passage has a shape of a substantially quadrangle including a first side extending along the first line from the starting point and a second side extending along the second line from the end point. The circuitry is configured to generate a travel route along which the work vehicle is to travel in the target work region.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority under 35 U.S.C. § 119 toJapanese Patent Application No. 2017-008344, filed Jan. 20, 2017 and toJapanese Patent Application No. 2017-008355, filed Jan. 20, 2017. Thecontents of these applications are incorporated herein by reference intheir entirety.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a travel route generation device and atravel route generation method.

Discussion of the Background

In recent years, a work vehicle that works while automatically travelingin a work field has been proposed. In order to cause a work vehicle totravel automatically in this way, it is necessary to generate a travelroute that serves as a travel target. In order to generate a travelroute that covers a work field, it is a precondition to accurately graspa shape of the work field. Since a work field such as a field is dividedby a private farm road or the like, it is difficult to determine anaccurate shape of the work field from a general map.

Therefore, Unexamined Japanese Patent Publication No. 2016-31649discloses teaching travel by which a manually operated tractor travelswithin a field to acquire external shape data of the field from a locusof the travel.

SUMMARY OF THE INVENTION

According to one aspect of the present invention, a travel routegeneration device includes a point input interface and circuitry.Positions of a starting point, an end point, and intermediate points ina work field are input. The intermediate points define a shape of thework field. The circuitry is configured to define a shape of the workfield by calculating a first line connecting the starting point and oneof the intermediate points, and a second line connecting another of theintermediate points and the end point. The first line and the secondline define the shape of the work field. The circuitry is configured tocalculate a shape of an entrance passage in the work field though whicha work vehicle is to enter a target work region in which the workvehicle is to work in the work field. The entrance passage has a shapeof a substantially quadrangle including a first side and a second side.The first side extends along the first line from the starting point. Thesecond side extends along the second line from the end point. Thestarting point and the end point are provided on a diagonal of thesubstantially quadrangle. The circuitry is configured to generate atravel route along which the work vehicle is to travel in the targetwork region.

According to another aspect of the present invention, a travel routegeneration device includes a point input interface and circuitry.Original positions of a starting point, an end point, and intermediatepoints in a work field are input via the point input interface, and theoriginal positions indicate positions of a work vehicle when a referencepoint provided at a corner of the work vehicle reaches the startingpoint, the end point, and the intermediate points, respectively. Theintermediate points define a shape of a target work region in which thework vehicle is to work in a work field. The circuitry is configured tocalculate positions of the starting point, the end point, and theintermediate points from the original positions of the starting point,the end point, and the intermediate points, respectively, based on adistance from a point of the work vehicle indicating the position of thework vehicle to the reference point. The circuitry is configured todefine the shape of the target work region by calculating a lineconnecting the starting point, the intermediate points, and the endpoint, the line defining the shape of the target work region. Thecircuitry is configured to generate a travel route along which the workvehicle is to travel in the target work region.

According to further aspect of the present invention, a travel routegeneration method includes inputting positions of a starting point, anend point, and intermediate points in a work field. The intermediatepoints define a shape of the work field. The shape of the work field isdefined by calculating a first line connecting the starting point andone of the intermediate points, and a second line connecting another ofthe intermediate points and the end point. The first line and the secondline define the shape of the work field. A shape of an entrance passagein the work field through which a work vehicle is to enter a target workregion in which the work vehicle is to work in the work field iscalculated. The entrance passage has a shape of a substantiallyquadrangle including a first side extending along the first line fromthe starting point and a second side extending along the second linefrom the end point. The starting point and the end point are provided ona diagonal of the substantially quadrangle. A travel route along whichthe work vehicle is to travel in the target work region is generated.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the invention and many of the attendantadvantages thereof will be readily obtained as the same becomes betterunderstood by reference to the following detailed description whenconsidered in connection with the accompanying drawings.

FIG. 1 is a schematic view illustrating how a work vehicle enters a workfield divided by a ridge through an entrance passage and measures ashape of the work field.

FIG. 2 is a side view of a tractor, which is one example of the workvehicle.

FIG. 3 shows a structure of the travel route generation device accordingto the embodiment of the present invention.

FIG. 4 is a flowchart illustrating a process of calculating shapes ofthe work field and the entrance passage in the travel route generationdevice.

FIG. 5 is a schematic view illustrating a relationship between aimingpoints set in the tractor and aiming point selection buttons displayedon a touch panel.

DESCRIPTION OF THE EMBODIMENTS

The embodiments will now be described with reference to the accompanyingdrawings, wherein like reference numerals designate corresponding oridentical elements throughout the various drawings.

A work vehicle equipped with a travel route generation device accordingto one exemplary embodiment of the present invention will be describedwith reference to the drawings. In this exemplary embodiment, the workvehicle is a tractor equipped with a work device 30 in a vehicle body 1.To begin with, the tractor is operated by a user to perform teachingtravel for calculating a field shape. In this teaching travel, thetractor enters a field through an entrance passage inclined downwardfrom a farm road, and performs circumferential travel along a boundaryof the field divided by a ridge. At that time, as will be described indetail later, a first endpoint on a ridge side of the entrance passageis position-registered as a starting point Ps, shape feature points thatprescribe the field shape are position-registered as intermediate pointsP1, P2, and P3, and a second endpoint facing the first endpoint on theridge side of the entrance passage is position-registered as an endpoint Pe. A basic shape of the field is calculated by a line thatconnects the starting point Ps, the intermediate points P1, P2, and P3,and the end point Pe. A region obtained by excluding the entrancepassage from this basic shape of the field is referred to as a targetwork region. Furthermore, a shape of the entrance passage is regarded asa quadrangle, a vertex that is adjacent to the target work region invertices other than the starting point Ps and the end point Pe isdefined as an inner point Pa, and a vertex distant from the target workregion is defined as an outer point Pb.

As illustrated in FIG. 2, this tractor is provided with a cab 20 in acentral portion of the vehicle body 1 supported by front wheels 11 andrear wheels 12. The tractor is equipped with the work device 30, whichis a rotary tilling machine, via a hydraulic lifting mechanism 31 at arear of the vehicle body 1. The front wheels 11 function as steeringcontrol wheels through which the tractor changes a travel direction whena steering angle of the steering control wheels is changed. The steeringangle of the front wheels 11 is changed by an operation of a steeringmechanism 13. The steering mechanism 13 includes a steering motor 14 forautomatic steering. For manual traveling, the front wheels 11 can besteered by operating a steering wheel 22 disposed in the cab 20. The cab20 is equipped with a general purpose terminal 4 that provides a userwith information and receives instructions from the user. In a cabin 21of the tractor, a satellite positioning module 80 is provided. As acomponent of the satellite positioning module 80, a satellite antennafor receiving a global navigation satellite system (GNSS) signal(including a GPS signal) is attached at a ceiling area of the cabin 21.Note that the satellite positioning module 80 may be combined with aninertial navigation module incorporated with a gyro acceleration sensorand a magnetic director sensor for complementing satellite navigation.As a matter of course, the inertial navigation module may be provided ina different location from the location of the satellite positioningmodule 80.

FIG. 3 illustrates a control system configured in this tractor. Thecontrol system of this exemplary embodiment includes a first controlunit, which is the general purpose terminal 4 including a graphical userinterface, a controlling unit 5 that controls the vehicle body 1 and thework device 30 of the tractor, and a remote controller 84 for wirelesslycontrolling travel start and travel stop of the tractor from outside.The travel route generation device according to the embodiment of thepresent invention is modularized as a route generation module 6, and isincorporated into the general purpose terminal 4.

In addition to the route generation module 6, the general purposeterminal 4 has functions of a general computer system, such as acommunication control unit 40, a touch panel 60 (a point input interface60), and an input/output management unit 61 that manages an inputoperation on the touch panel 60 and information display on the touchpanel 60. The general purpose terminal 4 is coupled to the controllingunit 5 in such a manner that the general purpose terminal 4 can exchangedata by vehicle-mounted LAN, wireless communication, cablecommunication, or the like. Furthermore, the general purpose terminal 4can exchange data with a control computer 100 configured in a remotecontrol center KS via a wireless channel or the Internet. In addition,it is also possible to carry the general purpose terminal 4 out of thetractor for use if the general purpose terminal 4 is configured as adevice such as a tablet computer and a cellular phone and isdata-exchangably coupled to the control system of the tractor.

In this exemplary embodiment, field information including a position ofthe field on a map and arrangement of farm roads surrounding the fieldis stored in a field information storage unit 101 of the controlcomputer 100, and this field information is needed for finding out thefield to work. The control computer 100 also includes a work planmanagement unit 102 that manages a work plan describing the work in aspecified field. The general purpose terminal 4 can access the controlcomputer 100, and download the field information from the fieldinformation storage unit 101 and the work plan from the work planmanagement unit 102. Alternatively, the general purpose terminal 4 canalso input the field information and the work plan via a recordingmedium such as a USB memory.

The route generation module 6 includes a work field shape calculationsubmodule 62 that calculates a shape of the target work region, which isa valid work region of the field, through the teaching travel, and atravel route generation unit 63 that generates a travel route for thetractor to travel in the target work region. The work field shapecalculation submodule 62 includes a starting point registration unit621, an intermediate point registration unit 622, an end pointregistration unit 623, a basic shape calculation unit 624, an entrancepassage information generation unit 625, and a shape editing unit 626.Furthermore, an inner point registration unit 627 is also prepared as anoption. Specifically, the general purpose terminal 4 includes a centralprocessing unit (CPU) 4P (circuitry 4P) and a memory 4M. Programs of theroute generation module 6 including the work field shape calculationsubmodule 62 and the travel route generation unit 63 are stored in thememory 4M and executed by the CPU 4P to perform a function of the routegeneration module 6.

Next, a basic role of each functional unit of the route generationmodule 6 will be described with reference to a flowchart of a fieldshape calculation process and a travel route generation processillustrated in FIG. 4. In FIG. 4, the field shape is a trapezoid, and anentrance passage inclined downward is provided at a right end of anupper side. Furthermore, as illustrated in FIG. 5, aiming points T1, T2,T3, and T4 are prescribed at four corners of the tractor. Distancesbetween these aiming points T1, T2, T3, and T4 and the own positionbased on positioning data from the satellite positioning module 80(illustrated with a black dot at the center of the vehicle body in FIG.5) are set in advance. Position coordinates of the aiming points T1, T2,T3, and T4 can be calculated from the own position. The touch panel 60displays aiming point selection buttons B1, B2, B3, and B4, and theaiming point corresponding to the pushed aiming point selection buttonB1, B2, B3, or B4 becomes valid in the following field shape calculationprocess.

The tractor that passes through a farm road and reaches the target fieldperforms teaching travel in order to calculate the shape of the field.Here, the aiming point selection button B1 is pushed, and the aimingpoint T1 is valid.

To begin with, a driver operates the tractor such that the tractorpasses through the entrance passage and that the aiming point T1 comesto a right end (first endpoint) after going down the entrance passage.The driver then pushes a registration button RB displayed on the touchpanel 60 (see FIG. 5). Accordingly, the starting point registration unit621 registers the first endpoint as a starting point (illustrated with ablack dot and Ps in FIG. 4).

Next, the driver advances the tractor such that the aiming point T1comes to a left end of the upper side, which is a shape feature point ofthe field (geometrical shape body, here, a vertex of the trapezoid), andthen pushes the registration button RB. Accordingly, the intermediatepoint registration unit 622 registers the left end of the upper side asa first intermediate point (illustrated with a black dot and P1 in FIG.4). Furthermore, the driver advances the tractor such that the aimingpoint T1 comes to a left end of a lower side, and then pushes theregistration button RB. Accordingly, the intermediate point registrationunit 622 registers the left end of the lower side as a secondintermediate point (illustrated with a black dot and P2 in FIG. 4).Furthermore, the driver advances the tractor such that the aiming pointT1 comes to a right end of the lower side, and then pushes theregistration button RB. Accordingly, the intermediate point registrationunit 622 registers the right end of the lower side as a thirdintermediate point (illustrated with a black dot and P3 in FIG. 4).

Next, the driver advances the tractor along the ridge (boundary) fromthe right end of the lower side of the field at which the thirdintermediate point is set, stops the tractor at a position at which theaiming point T1 comes to an endpoint that is an intersection of theentrance passage and the boundary, and then pushes the registrationbutton RB. Since the position at which the registration button RB ispushed is close to the starting point, the end point registration unit623 regards this position as an end point (illustrated with a black dotand Pe in FIG. 4) and registers the position. Alternatively, the drivermay instruct the end point registration unit 623 that the registeredposition is the end point, by performing an instruction operation ofindicating the end point and then pushing the registration button RB.

Accordingly, position coordinates of the starting point, the threeintermediate points, and the end point are obtained. The basic shapecalculation unit 624 connects these points to calculate the basic shapeof the work field.

Next, the entrance passage information generation unit 625 generatesentrance passage information, such as a shape and size of the entrancepassage and a travel direction in the entrance passage. As illustratedin FIG. 4, since the entrance passage is a partial passage, the entrancepassage may be substantially regarded as a quadrangle. Two oppositevertices of this quadrangle indicating the entrance passage are thestarting point and the end point (illustrated with black dots and Ps andPe in FIG. 4). Therefore, the shape and size of the entrance passage areobtained by calculating two more vertices. Therefore, when thisquadrangle indicating the entrance passage is regarded as aparallelogram (including a rectangle and a square) with extension linesof the boundary lines of the adjacent field (external shape extensionlines of the work field basic shape) as two sides, position coordinatesof a vertex inside the field (referred to as an outer point) and avertex outside the field (referred to as an inner point) can be easilycalculated by geometric calculation. In FIG. 4, the inner point isillustrated with a white circle and Pa, while the outer point isillustrated with a white circle and Pb. Furthermore, a direction from aside that connects the outer point and the end point to a side thatconnects the starting point and the inner point can be regarded as anentry direction (travel direction) of the tractor into the field.

A region other than the entrance passage in the field, that is, thetarget work region which is the valid work region is prescribed by acontour line obtained by connecting the starting point, the threeintermediate points, the end point, and the inner point. This contourline, which is substantially obtained by traveling of the tractor, isnot necessarily accurate. For example, when there are recessed orprotruding sections over which the tractor cannot travel, such recessedor protruding sections are neglected. Therefore, the shape editing unit626 is provided that modifies the contour line obtained by connectingthe starting point, the three intermediate points, the end point, andthe inner point. This shape editing unit 626 enables the user to editthe contour line displayed on the touch panel 60, for example, in amanner of editing a Bézier curve.

Note that when the optional inner point registration unit 627 can beused, after registration of the end point, the driver further operatesthe tractor such that the aiming point T1 comes to a right end (firstendpoint) downward along the entrance passage to an endpoint inside theboundary line of the entrance passage and the target work region, stopsthe tractor at a position to which the aiming point T1 comes, and thenpushes the registration button RB. Accordingly, the inner pointregistration unit 627 registers the position as the inner point(illustrated with a white circle and Pa in FIG. 4).

Although only the aiming point T1 has been used in the abovedescription, the other aiming points T2, T3, and T4 may be able toeasily approach a target position in some cases. In particular, whenapproaching backward, the aiming points T3 and T4 are convenient. Insuch a case, selecting and pushing a button corresponding to the desiredaiming point from the aiming point selection buttons B1, B2, B3, and B4cause the valid aiming point to be changed.

When the target work region is determined, the travel route generationunit 63 generates the travel route for the work vehicle to automaticallytravel in the target work region. In FIG. 4, the travel route to begenerated includes an inside travel route including straight movementroutes and U-turn routes that connect the straight movement routes, anda circumferential travel route for performing circumferential travel inan outer region of the field.

Specifically, the circumferential travel route is determined as follows.The outer region is also a region in which the tractor performs U-turntravel. A width of the outer region required for the U-turn travel ofthe tractor is calculated on the basis of a work width and anappropriate turning radius of the tractor. A turning count of thetractor is calculated. That is, the turning count is determined suchthat a value of an integral multiple (turning count) of the work widthof the tractor (accurately, work width in consideration of an overlapwidth) exceeds the width of the outer region necessary for U-turntravel. The actual width of the outer region is determined on the basisof this determined turning count. In general tilling work, a regioncorresponding to the two to three-round circumferential travel route isset as the outer region. A region inside the outer region serves as acentral region where the work travel of substantially straight movementis performed.

The straight movement routes are determined as follows. A referencestraight line that extends in parallel with a reference side of the workfield is determined. This reference straight line serves as a base forthe travel route in the central region. Determination of such areference straight line is pre-processing for generating the insidetravel route. At that time, a longest side of an approximate polygoncreated by an external shape of the field is generally employed as thereference side of the field. In the work field (field) as illustrated inFIG. 4, the external shape is an approximate quadrangle, and the longestside is selected as the reference side. Straight lines that are parallelwith this reference side and fill the central region in work width isset as the reference straight lines. Then, the reference straight linesin the central region are the straight movement routes, and generatesthe continuous inside travel routes by connecting the straight movementroutes with the U-turn routes.

As a matter of course, instead of this, an algorithm may be employedthat generates a spiral travel route along which the tractor travelsspirally in the field, and other travel routes.

As illustrated in FIG. 3, the controlling unit 5, which is a coreelement of the control system of the tractor, includes an outputprocessing unit 7 and an input processing unit 8, which respectivelyfunction as input and output interfaces, and a communication processingunit 70. The output processing unit 7 is coupled to devices equipped inthe tractor, such as vehicle travel instruments 71, work deviceinstruments 72, and a notification device 73. The vehicle travelinstruments 71 include the steering motor 14, and although notillustrated, devices to be controlled for allowing the vehicle totravel, such as a transmission mechanism and an engine unit. The workdevice instruments 72 include devices such as a drive mechanism for thework device 30 and the lifting mechanism 31 that raises and lowers thework device 30. The notification device 73 includes a display, lamps,and a speaker. The notification device 73 is used for notifying thedriver or supervisor of attention information and warning information,such as travel precautions and deviation from the target travel routewhen the work vehicle is automatically steered. The communicationprocessing unit 70 has a function of transmitting data processed by thecontrolling unit 5 to the control computer 100, and receiving variouskinds of data from the control computer 100. Furthermore, thecommunication processing unit 70 inputs remote control instructions fromthe remote controller 84.

The input processing unit 8 is coupled to, for example, the satellitepositioning module 80, travel system detection sensors 81, work systemdetection sensors 82, and an automatic/manual switch 83. The travelsystem detection sensors 81 include sensors for detecting travel statessuch as an engine speed and a transmission state. The work systemdetection sensors 82 include sensors for detecting a position andinclination of the work device 30, sensors for detecting workloads, andthe like. The automatic/manual switch 83 is a switch for selectingeither an automatic travel mode for traveling with automatic steering ora manual steering mode for traveling with manual steering.

Furthermore, the controlling unit 5 includes a travel control unit 50, awork control unit 54, an own position calculation unit 53, a travelroute setting unit 55, and a notification unit 56. Based on positioningdata sent from the satellite positioning module 80, the own positioncalculation unit 53 calculates the own position. During theabove-described teaching travel, the calculated own position is providedto the work field shape calculation submodule. Since the automatictravel (automatic steering) mode and the manual travel (manual steering)mode are both configured to be available in this tractor for traveling,the travel control unit 50 for controlling the vehicle travelinstruments 71 includes a manual travel control unit 51 and an automatictravel control unit 52. In accordance with operations of the driver, themanual travel control unit 51 controls the vehicle travel instruments71. The automatic travel control unit 52 calculates discrepancies indirection and position between the travel route that is set by thetravel route setting unit 55 and the own position, and generates anautomatic steering instruction. This automatic steering instruction isoutput to the steering motor 14 via the output processing unit 7. Theautomatic travel control unit 52 stops the tractor on the basis of astop instruction from the remote controller 84, and causes the tractorto start travel on the basis of a starting instruction from the remotecontroller 84. To control movement of the work device 30, the workcontrol unit 54 provides control signals to the work device instruments72. The notification unit 56 generates notification signals (displaydata and voice data) for notifying information necessary for the driveror the supervisor, and provides the notification signals to thenotification device 73 incorporated into an instruments panel.

The travel route setting unit 55 receives the travel route generated bythe route generation module 6 via the communication processing unit 70from the travel route generation unit 63 of the general purpose terminal4. The travel route setting unit 55 then sets the travel route as atarget travel route for the tractor.

OTHER EMBODIMENTS

(1) In the above-described exemplary embodiment, the position and shapeof the entrance of the work field is calculated, the target work region,which is a region obtained by excluding the entrance from the workfield, is calculated, and the travel route for automatically travelingin the target work region is generated. Instead of this exemplaryembodiment, an exemplary embodiment may be employed that calculates ashape of an arbitrary region in the work field as the target work regionand generates the travel route independently of the entrance. In such atravel route generation device, the entrance passage informationgeneration unit 625 and the inner point registration unit 627 becomeunnecessary in the work field shape calculation submodule 62 of theroute generation module 6.

(2) In the above-described exemplary embodiment, the tractor used foractual work is equipped with the route generation module 6, and theaiming points T1, T2, T3, and T4 are also prescribed at corners of thetractor. Instead of this, a vehicle other than the tractor, for example,a multiple-purpose vehicle that can travel in the work field (field) ata higher speed and includes a satellite positioning function may beequipped with the route generation module 6 or the work field shapecalculation submodule 62 to calculate the shape of the work field(field).

(3) Hardware and programs in the diagram illustrated in FIG. 3 areclassified mainly for purposes of description. Actually, each of thehardware and programs can be integrated with another hardware or otherprograms. Alternatively, each of the hardware and programs can bedivided into pieces of hardware or a plurality of programs. For example,the route generation module 6, in particular, the travel routegeneration unit 63 may be configured within the controlling unit 5 ofthe work vehicle.

(4) The tractor equipped with the rotary tilling machine as the workdevice 30 has been described as the work vehicle in the above-describedexemplary embodiment. In addition to such a tractor, for example, theexemplary embodiment is applicable to agricultural vehicles includingrice transplanters, fertilizer distributors, and combines.

INDUSTRIAL APPLICABILITY

The travel route generation device according to the embodiment of thepresent invention is applicable to the work vehicle that works along theset travel route in the work field.

A travel route generation device according to the embodiment of thepresent invention is a device for a work vehicle that enters and leavesa work field divided by a boundary through an entrance passage, thetravel route generation device including: a starting point registrationunit that position-registers a first endpoint on a side of the boundaryof the entrance passage as a starting point; an intermediate pointregistration unit that position-registers a shape feature point thatprescribes a shape of the work field as an intermediate point; an endpoint registration unit that position-registers a second endpoint facingthe first endpoint on a side of the boundary of the entrance passage asan end point; a basic shape calculation unit that calculates a basicshape of the work field by connecting a position of the starting point,a position of the intermediate point, and a position of the end point;an entrance passage information generation unit that generates entrancepassage information with a quadrangle as a shape of the entrancepassage, the quadrangle having the starting point and the end point asopposite vertices and having two sides along an external shape extensionline of the basic shape; and a travel route generation unit that definesa region other than the entrance passage of the work field as a targetwork region, and generates a travel route for the work vehicle toautomatically travel in the target work region.

Note that terms indicating geometrical shapes used in the embodiment ofthe present invention, for example, a triangle, a quadrangle, arectangle, and a polygon are not used in order to identify ageometrically strict shape, but are used in order to describe such ashape almost as a whole. Therefore, each side of a polygon is not alwaysa straight line and may be slightly bended or uneven.

This configuration allows calculation of the basic shape of the workfield by connecting the position of the starting point, the position ofthe intermediate point, and the position of the end point acquired inmovement along the boundary of the work field that leaves one end of theentrance passage and returns to the other end of the entrance passage.The work field is regarded as a polygon and the intermediate pointcorresponds to a polygon vertex, which is a feature point of the shape.When the work field is a triangle, the number of intermediate points istwo, when the work field is a quadrangle, the number of intermediatepoints is three, and when the work field is a pentagon, the number ofintermediate points is four. The entrance passage can be regarded as aquadrangle that is substantially a rectangle. Since the starting pointand the end point correspond to opposite vertices of the rectangle, theshape of the rectangle indicating the entrance passage can becalculated. Accordingly, the basic shape of the work field is a polygonin which a small rectangle (quadrangle) is interposed at a placecorresponding to the entrance passage. Therefore, the target work regionin which the work vehicle needs to work is obtained by removing therectangle indicating the entrance passage from the calculated work fieldshape. The travel route generation unit generates the travel route thatcovers this target work region, thereby providing the travel route thatcauses neither problem that the travel route and the entrance passageoverlap each other nor problem that the travel route is distant from theentrance passage.

Since the entrance passage is inclined in the work field such as afield, it is important that travel of the work vehicle that enters thetarget work region from the entrance passage is straight movement andthat travel of the work vehicle immediately before leaving the targetwork region for the entrance passage is straight movement. Accordingly,it is important to consider a travel direction of the work vehicle inthe entrance passage as one of conditions of travel route generation.Therefore, it is advantageous when the travel direction in the entrancepassage is also calculated in addition to the shape of the entrancepassage. For this object, according to one advantageous exemplaryembodiment of the present invention, the entrance passage informationgeneration unit defines vertices other than the starting point and theend point of the quadrangle representing the shape of the entrancepassage as an inner point that is adjacent to the target work region andan outer point distant from the target work region, and a direction froma side connecting the outer point and the end point to a side connectingthe starting point and the inner point is an entry direction of the workvehicle into the target work region.

When it is assumed that the shape of the entrance passage is aquadrangle, the inner point and the outer point can be calculated fromthe positions of the starting point and the end point, which areopposite vertices of the quadrangle. Since the position of the innerpoint determines a boundary of the entrance passage and the target workregion, it is preferable to detect as actual position as possible.Therefore, according to one advantageous exemplary embodiment of thepresent invention, an inner point registration unit is provided thatdefines vertices other than the starting point and the end point of thequadrangle representing the shape of the entrance passage as an innerpoint that is adjacent to the target work region and an outer pointdistant from the target work region, and registers the inner point.Employing the inner point registered as an actual position allows moreaccurate calculation of the shape of the entrance passage.

Position coordinates needed for position-registration of the startingpoint, the intermediate point, and the end point may be a work fieldcoordinate system or a latitude longitude system. However, a satellitepositioning module is mounted on the work vehicle that travelsautomatically, and it is advantageous to use this satellite positioningmodule. Therefore, according to one advantageous exemplary embodiment ofthe present invention, position-registration of the starting point, theintermediate point, and the end point is performed through traveling ofthe work vehicle along the boundary, and the positions of the startingpoint, the intermediate point, and the end point are calculated using anown position based on positioning data from a satellite positioningmodule mounted on the work vehicle. With this configuration, since thework vehicle itself is used as a position measuring instrument, movementfor work field shape measurement is easy even if the work field is vast.A position detecting system using the satellite positioning modulemounted on the work vehicle is used, which is advantageous in terms ofcost as well.

When the work vehicle itself is used as a position measuring instrument,even when the work vehicle approaches the shape feature point of thework field (a vertex of a polygon), there is a distance between the ownposition that is typically set for automatic travel and the position ofthe shape feature point. In order to solve a positional error caused bythis distance, one advantageous exemplary embodiment of the presentinvention is configured such that one or more aiming points associatedwith the positions of the starting point, the intermediate point, andthe end point are prescribed at corners of the work vehicle, and thepositions of the starting point, the intermediate point, and the endpoint are calculated by modifying the own position according todistances from the own position to the aiming points. This enables thework vehicle to measure the positions accurately only by causing anappropriate corner (aiming point) of the work vehicle to approach theshape feature point of the work field. Preferably, setting such aimingpoints at a front right end, front left end, rear right end, and rearleft end of the work vehicle and selecting one of the four ends allowthe aiming point to smoothly match the shape feature point of the workfield.

The embodiment of the present invention is also applied to a travelroute generation device that calculates a shape of an arbitrary regionin the work field as the target work region and generates the travelroute independently of the entrance. Such a travel route generationdevice for a work vehicle includes: a starting point registration unitthat position-registers a first endpoint of a target work region forwork travel as a starting point; an intermediate point registration unitthat position-registers a shape feature point that prescribes a shape ofthe target work region as an intermediate point; an end pointregistration unit that position-registers the first endpoint or a secondendpoint adjacent to the first endpoint as an end point; a basic shapecalculation unit that calculates a basic shape of the target work regionby connecting a position of the starting point, a position of theintermediate point, and a position of the end point; and a travel routegeneration unit that generates a travel route for the work vehicle toautomatically travel in the target work region, wherein one or moreaiming points associated with the positions of the starting point, theintermediate point, and the end point are prescribed at corners of thework vehicle or a vehicle capable of traveling in the target workregion, and the positions of the starting point, the intermediate point,and the end point are calculated by modifying an own position accordingto distances from the own position to the aiming points. This travelroute generation device, which uses the work vehicle or a vehiclecapable of traveling in the target work region as a position measuringinstrument, can calculate the shape smoothly even if the target workregion is vast.

Functions of the travel route generation device described above can besubstantially implemented by execution of a computer program installedin a computer. Therefore, the scope of the present invention also coverssuch a computer program. A travel route generation program according tothe embodiment of the present invention is a program for a work vehiclethat enters and leaves a work field divided by a boundary through anentrance passage. The travel route generation program causes a computerto execute: a starting point registration function ofposition-registering a first endpoint on a side of the boundary of theentrance passage as a starting point; an intermediate point registrationfunction of position-registering a shape feature point that prescribes ashape of the work field as an intermediate point; an end pointregistration function of position-registering a second endpoint facingthe first endpoint on a side of the boundary of the entrance passage asan end point; a basic shape calculation function of calculating a basicshape of the work field by connecting a position of the starting point,a position of the intermediate point, and a position of the end point;an entrance passage information generation function of generatingentrance passage information with a quadrangle as a shape of theentrance passage, the quadrangle having the starting point and the endpoint as opposite vertices and having two sides along an external shapeextension line of the basic shape; and a travel route generationfunction of defining a region other than the entrance passage of thework field as a target work region, and generating a travel route forthe work vehicle to automatically travel in the target work region.Functions and effects of this travel route generation program areidentical to functions and effects of the above-described travel routegeneration device. In addition, the above-described advantageousexemplary embodiment of the travel route generation device is alsoapplicable to this travel route generation program.

Similarly, the embodiment of the present invention is also applied to atravel route generation program that calculates a shape of an arbitraryregion in the work field as a target work region and generates a travelroute independently of the entrance. This travel route generationprogram for a work vehicle causes a computer to execute: a startingpoint registration function of position-registering a first endpoint ofa target work region for work travel as a starting point; anintermediate point registration function of position-registering a shapefeature point that prescribes a shape of the target work region as anintermediate point; an end point registration function ofposition-registering the first endpoint or a second endpoint adjacent tothe first endpoint as an end point; a basic shape calculation functionof calculating a basic shape of the target work region by connecting aposition of the starting point, a position of the intermediate point,and a position of the end point; a travel route generation function ofgenerating a travel route for the work vehicle to automatically travelin the target work region; and a function of calculating the positionsof the starting point, the intermediate point, and the end point, bymodifying an own position according to distances from the own positionto one or more aiming points associated with the positions of thestarting point, the intermediate point, and the end point, the aimingpoints being prescribed at corners of the work vehicle or a vehiclecapable of traveling in the target work region. Functions and effects ofthis travel route generation program are also identical to the functionsand effects of the above-described travel route generation device. Inaddition, the above-described advantageous exemplary embodiment of thetravel route generation device is also applicable to this travel routegeneration program.

Obviously, numerous modifications and variations of the presentinvention are possible in light of the above teachings. It is thereforeto be understood that within the scope of the appended claims, theinvention may be practiced otherwise than as specifically describedherein.

What is claimed is:
 1. A travel route generation device comprising: apoint input interface via which positions of a starting point, an endpoint, and intermediate points in a work field are input, theintermediate points defining a shape of the work field; circuitryconfigured to define the shape of the work field by calculating a firstline connecting the starting point and one of the intermediate points,and a second line connecting another of the intermediate points and theend point, the first line and the second line defining the shape of thework field, calculate a shape of an entrance passage in the work fieldthrough which a work vehicle is to enter a target work region in whichthe work vehicle is to work in the work field, the entrance passagehaving a shape of a substantially quadrangle comprising: a first sideextending along the first line from the starting point; and a secondside extending along the second line from the end point, the startingpoint and the end point being provided on a diagonal of thesubstantially quadrangle, and generate a travel route along which thework vehicle is to travel in the target work region.
 2. The travel routegeneration device according to claim 1, wherein the substantiallyquadrangle has vertices including the starting point, the end point, aninner point, and an outer point, the inner point being provided on thetarget work region, the first side and the second side connecting at theouter point, and wherein a direction from the second side to a thirdside connecting the starting point and the inner point is an entrydirection of the work vehicle into the target work region.
 3. The travelroute generation device according to claim 2, wherein a position of theinner point is input via the point input interface.
 4. The travel routegeneration device according to claim 1, wherein the substantiallyquadrangle has vertices including the starting point, the end point, aninner point, and an outer point, the inner point being provided on thetarget work region, the first side and the second side connecting at theouter point.
 5. The travel route generation device according to claim 1,wherein the positions of the starting point, the intermediate points,and the end point are input via the point input interface while the workvehicle travels along a boundary of the work field, and wherein thepositions of the starting point, the intermediate points, and the endpoint are calculated using a position of the work vehicle based onpositioning data from a satellite positioning module mounted on the workvehicle.
 6. The travel route generation device according to claim 5,wherein the work vehicle has a reference point out of at least onecorner point positioned at at least one corner of the work vehicle, andwherein the positions of the starting point, the intermediate points,and the end point are calculated by modifying the position of the workvehicle based on a distance from a point of the work vehicle indicatingthe position of the work vehicle to the reference point.
 7. A travelroute generation device comprising: a point input interface via whichoriginal positions of a starting point, an end point, and intermediatepoints in a work field are input, the original positions indicatingpositions of a work vehicle when a reference point provided at a cornerof the work vehicle reaches the starting point, the end point, and theintermediate points, respectively, the intermediate points defining ashape of a target work region in which the work vehicle is to work in awork field; and circuitry configured to calculate positions of thestarting point, the end point, and the intermediate points from theoriginal positions of the starting point, the end point, and theintermediate points, respectively, based on a distance from a point ofthe work vehicle indicating the position of the work vehicle to thereference point, define the shape of the target work region bycalculating a line connecting the starting point, the intermediatepoints, and the end point, the line defining the shape of the targetwork region, and generate a travel route along which the work vehicle isto travel in the target work region.
 8. The travel route generationdevice according to claim 6, wherein the reference point is selectablefrom points provided at corners of the work vehicle.
 9. The travel routegeneration device according to claim 1, wherein the first line, thefirst side, the second line, the second side, and a line passing throughthe intermediate points define the shape of the work field.
 10. Thetravel route generation device according to claim 1, wherein thecircuitry is configured to generate an entrance passage informationincluding an information of the shape of the entrance passage.
 11. Thetravel route generation device according to claim 1, wherein the workvehicle is to travel automatically in the travel route.
 12. A travelroute generation method comprising: inputting positions of a startingpoint, an end point, and intermediate points in a work field, theintermediate points defining a shape of the work field; defining theshape of the work field by calculating a first line connecting thestarting point and one of the intermediate points, and a second lineconnecting another of the intermediate points and the end point, thefirst line and the second line defining the shape of the work field;calculating a shape of an entrance passage in the work field throughwhich a work vehicle is to enter a target work region in which the workvehicle is to work in the work field, the entrance passage having ashape of a substantially quadrangle including a first side extendingalong the first line from the starting point and a second side extendingalong the second line from the end point, the starting point and the endpoint being provided on a diagonal of the substantially quadrangle; andgenerating a travel route along which the work vehicle is to travel inthe target work region.